Optic fibers receive less interference from the external environment and have a low rate of information loss. Thus, the optic fibers are widely used in various fields for transmitting or detecting information of a general communications network, a cable broadcasting network, and various automatic devices. A sensor using the optic fibers functions as a detector by using elasticity depending on temperature or pressure, a phase difference of light or the Doppler effect. To be specific, the sensor is used for many purposes such as a temperature sensor, a pressure sensor, a gyroscope, a speedometer, a windvane, and a gas leak sensor. In particular, a sensor used for detecting gases, compounds, biomolecules, and the like has received a lot of attention for a long time and a lot of research thereof has been published. The gas sensor has been used in various fields such as chemistry, pharmaceuticals, environment, and medical treatment and is expected to be researched further in the future. As social demands such as environmental preservation and safety management increase, performance and specifications required for the gas sensor have been advanced.
In response to such demands for the gas sensor of high sensitivity and high performance, a lot of research on new materials for the gas sensor has been carried out and applications of new materials of high sensitivity to the gas sensor have been made.